In recent years, there has been vigorous development of flat panel displays, and among those, liquid crystal displays have garnered attention due to advantages such as being light weight, and having a thin profile and low power consumption. In particular, among active matrix type liquid crystal displays having switching elements in each pixel, modes relying on horizontal electric fields (including fringe fields) such as in-plane switching (IPS) mode and fringe field switching (FFS) mode have garnered attention. Moreover, especially recently, higher resolution displays have been sought mainly in portable electronic devices such as smartphones and tablet PCs in order to improve display quality, and further reduction in power consumption is demanded in order for the battery to last longer.
Liquid crystal displays of a horizontal electric field-driven mode such as IPS mode and FFS mode include pixel electrodes and a common electrode (opposite electrode) formed on an array substrate, and liquid crystal molecules are switched by an electric field substantially parallel to the main surface of the array substrate. In addition, a pair of polarizing plates are disposed on the array substrate and the opposite substrate, the pair of polarizing plates being disposed such that the respective polarizing axes thereof are perpendicular to each other. By such an arrangement of polarizing plates, a black screen is displayed when no voltage is being applied, and a white screen is displayed by gradually increasing the transmittance by applying a voltage corresponding to an image signal to the pixel electrodes, for example. In such a liquid crystal display, the liquid crystal molecules rotate on a plane substantially parallel to the respective main surfaces of the array substrate and the opposite substrate, and thus, the polarizing state of the transmitted light does not greatly change depending on the angle of incidence of the light. Thus, such liquid crystal displays have characteristics such as having a low dependence on the viewing angle, and having a wide viewing angle.
IPS mode liquid crystal displays have gate electrodes, drain electrodes, source electrodes, semiconductor films, gate insulating films, a common electrode, and a protective insulating film formed on a glass substrate, for example, and among horizontal electric field-driven liquid crystal displays in which images are displayed by driving liquid crystal molecules by an electric field substantially parallel to the glass substrate surface, a liquid crystal display is disclosed in which the common electrode, and the source electrode and drain electrode are separated by an insulating film, thereby placing them in different layers, and a portion of the common electrode and source electrode overlap across the insulating film to form additional capacitance (see Patent Document 1, for example).
Furthermore, among active matrix type liquid crystal displays, a technique is disclosed in which the opposite electrode and the pixel electrodes are formed in a linear fashion so as not to overlap in a plan view to be able to generate an electric field parallel to the substrate surfaces, an insulating film having a relative permittivity of 4 or less is formed on the source bus line, and the opposite electrode is formed on the insulating film so as to cover the source bus line (see Patent Document 2, for example).
Additionally disclosed is a liquid crystal display including an array substrate having pixel electrodes disposed for the respective pixels, an opposite substrate disposed opposite to the array substrate and including an opposite electrode common to the plurality of pixels, and a liquid crystal layer held between the array substrate and the opposite substrate, the pixel electrodes having strip-shaped linear portions, the opposite electrode including strip-shaped linear portions disposed alternately and in parallel with the linear portions of the pixel electrodes so as to be able to form a horizontal electric field with the linear portions of the pixel electrodes (see Patent Document 3, for example).